AI voice agents · October 2026 Edition
Retell AI vs Synthflow
Five of fourteen models named Retell AI first on the direct prompt; one named Synthflow. Retell AI was named by fourteen of the fourteen models and Synthflow by thirteen and Retell AI carries 58 labels and Synthflow 32, so the shares are not directly comparable.
Named in two categories this edition.
Named in two categories this edition.
First-choice share27%3%Of first choices across the direct, paraphrase, budget and scale prompts, 0 to 100.
Negative rate16%22%Negative labels as a share of the product's labels, 0 to 100.
Rank in category#1#5A position in a field of 8; printed, not drawn.
Labels5832A count; the two differ.
The two percentage rows are drawn on one 0 to 100 track, Retell AI reading right to left. Rank and label count are printed, not drawn.CloudTalk was named alongside these two in ten of the fourteen direct answers. Retell AI vs CloudTalk · Retell AI vs Vapi · Retell AI vs Bland AI
Share is the count of first choices across the direct, paraphrase, budget and scale prompts over all fourteen models, for a mid-market B2B company; rank is within the category; every quote names the model and the prompt it came from. Both figures come from the AI voice agents page.
By framing
How many of the fourteen models made each the first choice, per way of asking, and how many argued against it.
Retell AIFirst choices, of fourteen modelsSynthflow
Direct511 against Synthflow
Paraphrase30
Comparative60
Budget-constrained711 against Synthflow
Scale-constrained20
Negative109 against Retell AI · 5 against Synthflow
Bars are first choices, 0 to 14 each sideModels that argued againstA model can name both, so the two sides of a row do not sum to fourteen.
Across every category in the October 2026 Edition, Retell AI and Synthflow were named in the same answer sixty-six times, of the 158 answers naming Retell AI and the 79 naming Synthflow. In those answers Synthflow took the first choice seven times and Retell AI twenty-three.
Every model, every framing
The eighty-four answers behind the chart above, one cell each: where Retell AI and Synthflow stood in it.
| Model | Direct | Paraphrase | Comparative | Budget-constrained | Scale-constrained | Negative |
|---|---|---|---|---|---|---|
| Claude Haiku 4.5 | | | | | | |
| GPT-5.4 mini | | |||||
| Gemini 3.5 Flash | | | | | | |
| Perplexity Sonar | | | | | ||
| Grok 4.1 Fast | | | | | | |
| Mistral Small | | | | |||
| DeepSeek V4 Flash | | | | | | |
| Llama 4 Maverick | | | ||||
| Qwen 3.7 Flash | | | | | ||
| Kimi K2 | | | | | | |
| GLM 4.7 FlashX | | | | |||
| MiniMax M2.5 | | | | |||
| GPT-6 Luna | | | | | ||
| Muse Glimmer 30B | | | | |
Retell AI Synthflow first choice named as an alternative argued againstblank: not namedEach cell is one answer, Retell AI on the left and Synthflow on the right.The direct prompt
The plain question, one answer per model, grouped by where Retell AI and Synthflow stood in it.
Retell AI first, Synthflow an alternative
5 of 14 modelsSynthflow was named in the answer but not as the choice, or not at all.Claude Haiku 4.5Aloware, Retell AI alternatives: Synthflow, Vapi
Grok 4.1 FastRetell AI alternatives: Bland AI, CloudTalk, Regal, Synthflow
Mistral SmallCloudTalk, Retell AI alternatives: ElevenLabs Conversational AI, Leaping AI
DeepSeek V4 FlashRegal, Retell AI alternatives: CloudTalk, Synthflow AI
GPT-6 LunaRetell AI alternatives: PolyAI, Synthflow, Vapi
Synthflow first, Retell AI an alternative
1 of 14 modelsRetell AI was named in the answer but not as the choice, or not at all.MiniMax M2.5CloudTalk, Synthflow alternatives: Retell AI
Neither was the first choice, one was named
6 of 14 modelsThe answer put something else first and named one of the two as an alternative.Gemini 3.5 FlashAloware, Synthflow AI alternatives: Bland AI, Retell AI, Vapi
Perplexity SonarCloudTalk alternatives: Retell AI, Salesforce Agentforce Voice, Synthflow AI
Qwen 3.7 FlashCloudTalk alternatives: Bland AI, Retell AI, Rezora IO
Kimi K2CloudTalk alternatives: Aloware, Retell AI, Synthflow
GLM 4.7 FlashXCloudTalk alternatives: Bland AI, Retell AI, Synthflow, Vapi.ai
Muse Glimmer 30BAloware, CloudTalk alternatives: HubSpot Breeze AI, Retell AI, Synthflow
Neither was named
2 of 14 modelsThe answer made no first choice from these two in this category.GPT-5.4 miniTwilio alternatives: Deepgram Voice Agent API, OpenAI Realtime / Voice agents
Llama 4 MaverickAloware, CloudTalk alternatives: GetVoIP, Plivo
Bold names in an answer are the products the judge labeled a first choice; a model naming several gives each of them that label. The full answer text for every row is in the record.
By buyer segment
The same question asked on behalf of a different buyer. Each standing is computed within its segment and they are never added together. The figures above are the mid-market standing, which is the one the category orders by.
Small business
Retell AI leads by eight points.
Retell AI20%#1 of 7Synthflow12%#3 of 7Mid-marketThe figures above
Retell AI leads by twenty-four points.
Retell AI27%#1 of 8Synthflow3%#5 of 8Enterprise
Retell AI leads by twelve points.
Retell AI14%#2 of 11Synthflow2%#11 of 11What the models said about Retell AI
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Six of eight in this category shown.
“some specific products (for example Synthflow, ElevenLabs, Retell AI, Deepgram) have recurring complaints about cost or credit limits” GPT-5.4 mini · negative prompt · soft negative
“Both Vapi.ai and Retell AI can suffer from latency and reliability issues due to reliance on external API providers” Claude Haiku 4.5 · negative prompt · soft negative
“While popular among developers, there is significant frustration in the community regarding its operational setup.” Qwen 3.7 Flash · negative prompt · soft negative
“Best all-around voice AI platform for production call automation... "best overall — lowest effective cost, highest voice quality, full API and no-code in one platform"” Muse Glimmer 30B · comparative prompt · first choice
“Strong all-around balance of latency, price, and accessibility; often described as a fast, transparent usage-based option with native telephony and quick setup.” Perplexity Sonar · comparative prompt · first choice
“*Developer-first / Infrastructure:* Vapi, Retell AI, Vocode, or Bland.ai. (Excellent for high customization, low latency, and BYO keys).” Gemini 3.5 Flash · scale prompt · first choice
What the models said about Synthflow
Every negative label with a quote, up to three, then the highest-weighted positives, up to three. Six of seven in this category shown.
“Why avoid: If your call volumes exceed 5,000 calls per month, Synthflow may not scale well for you.” Mistral Small · negative prompt · hard negative
“Enterprise-heavy (e.g., Synthflow: $30k/year min).” Grok 4.1 Fast · budget prompt · hard negative
“some specific products (for example Synthflow, ElevenLabs, Retell AI, Deepgram) have recurring complaints about cost or credit limits” GPT-5.4 mini · negative prompt · soft negative
“The best AI voice agent platform for a company with a limited budget is Synthflow, as it offers a finished no-code agent at a low cost.” Llama 4 Maverick · budget prompt · first choice
“Synthflow or CloudTalk offer the best balance of ease-of-use, features, and pricing” MiniMax M2.5 · direct prompt · first choice
“Want a no-code visual builder that deploys quickly across sales and support with multilingual support → Synthflow.” Muse Glimmer 30B · direct prompt · alternative
Also compared
Comparisons are drawn for the top eight products in each category, each against each. The output is the models' output; nothing here is a recommendation by the index.